Autofocus and video performance

Autofocus

The E-M10 III's autofocus is solely based on contrast detection. In other words, it measure the contrast in the part of the scene it's focusing on, moves the lens and checks again, then continues to move the lens in whichever direction results in improved contrast (and a sharper image). This is an excellent way of ensuring perfect focus when shooting static subjects.

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Traditionally, it's been a less positive story for moving subjects and continuous autofocus. This is because, even if you can move the lens and check contrast really quickly, there's a risk that your subject will have moved while you were taking measurements: the focus distance giving the highest contrast is literally a moving target.

The results both of our testing and our experiences shooting with the camera were distinctly mixed.

To check the camera's ability to refocus and drive the lens fast enough, the first part of test features the riding traveling towards the camera in a straight line with a single, central AF point selected. Despite the reliance on contrast-detection AF, you can see the E-M10 III does very well at this.

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If you make the challenge more difficult, by expecting the camera to recognize and track the subject around the frame, rather than just refocusing in a single position, it does less well. We found it would sometimes track pretty tenaciously, at which point we'd get around 2/3rds of the image in useable or perfect focus. However, on other occasions the camera would lose the subject and revert to focusing on the background.

While there were some runs where the camera kept track of the cyclist pretty well, there were too many instances where it just took an interest in the background.

Our everyday use of the camera yielded similar results: sometimes the camera would do well, other times it would produce a run of out-of-focus images. The upshot was that we didn't feel we could trust C-AF + Tracking mode enough to use it.

Video quality

The E-M10 III's 4K video quality is really pretty good. Fine detail isn't captured as precisely as some of its peers, but the end result, especially with the application of Olympus's excellent JPEG color, is really pretty solid for a camera at this price.

A 1.2x crop is applied when you engage Digital IS (called MIS-1 on the camera), which makes wide-angle shots virtually impossible, but the footage looks very similar to the unstabilized version, so you can engage it as needed.

And, while there is some softness to the footage, it doesn't change significantly when you crop in to provide the impressive digital+mechanical stabilization, meaning you should be able to intercut between footage without most viewers spotting the difference.

Video Autofocus

Contrast detection's other real weakness tends to be in video shooting: any overshoot the camera needs to confirm that peak focus has been reached and exceeded, makes video looks wobbly. This usually means having to manual focus or, at least, to use Single AF to acquire focus before you hit record.